1. Field of the Invention
The present invention relates to a voice transmitter for transmitting an audio signal and a DTMF signal (Dual Tone Multi-Frequency) by high-efficiency voice encoding technology.
2. Description of Related Art
FIG. 27 is a block diagram showing a conventional voice transmitter.
Referring to FIG. 27, reference numeral 8 denotes an input terminal of the voice transmitter; 9 an output terminal of the voice transmitter; 10 a voice encoding unit for encoding an audio signal; 11 a DTMF encoding unit for encoding a DTMF signal; 12 a DTMF detecting unit for detecting and judging whether or not an input signal is a DTMF signal; and 13 a selector for selecting an output of the voice encoding unit 10 or that of the DTMF encoding unit 11 under the control of the DTMF detecting unit 12, and for outputting either of them.
Next, the operation of the conventional voice transmitter will be described.
In the voice encoding unit 10 and the DTMF encoding unit 11, an inputted audio signal or a DTMF signal is encoded into digital data string. The voice encoding unit 10 encodes the signal by voice encoding technology. In addition, the DTMF encoding unit 11 decodes the DTMF audio signal into a DTMF numerical value. On the other hand, the DTMF detecting unit 12 detects and judges whether or not an input signal is a DTMF signal. If the input signal is a DTMF signal, the DTMF detecting unit 12 controls the selector 13 so that the output of the DTMF encoding unit 11 is selected. Otherwise, the DTMF detecting unit 12 controls the selector 13 so that the output of the voice encoding unit 10 is selected. The selector 13 selects an input signal in response to an instruction from the DTMF detecting unit 12, and then outputs the selected signal to the transmission line side.
FIG. 28 is a block diagram showing a conventional voice encoder described in JP-A No. 8-307366.
Referring to FIG. 28, reference numeral 111 denotes an input terminal; 112 a DTMF detection circuit for detecting and judging whether or not a signal, which is inputted by the input terminal 111, is a DTMF signal; 113 a DTMF encoder for encoding a DTMF signal; and 114 a voice encoder for encoding an audio signal. Reference numeral 112a denotes a switching circuit for selecting an output to the voice encoder 114 or that to the DTMF encoder 113, and for outputting either of them under the control of the DTMF detection circuit 112. Reference numeral 115 denotes an output selecting circuit for selecting an output of the voice encoder 114 or that of the DTMF encoder 113 under the control of the DTMF detection circuit 112, and for transmitting the selected output to an output terminal 116.
Next, the operation of the conventional voice encoder will be described.
In the DTMF signal detecting circuit 112, an inputted audio signal or a DTMF signal is judged whether or not it is a DTMF signal. The switching circuit 112a, which is notified that the signal is a DTMF signal, connects an input signal from the input terminal 111 to the DTMF encoder 113. The DTMF signal, which is given to the DTMF encoder 113, is encoded (i.e., decoded), is converted into a DTMF numerical value, and is then output as an encoded DTMF signal. Moreover, the output selecting circuit 115, which is notified that the signal is a DTMF signal, selects the output from the DTMF encoder 113 and outputs it to the output terminal 116. On the other hand, if the DTMF detecting circuit 112 judged the signal not to be a DTMF signal, each of the switching circuit 112a and the output selecting circuit 115, which is notified that the signal is not a DTMF signal, connects an input signal from the input terminal 111 to the voice encoder 114, selects an output from the voice encoder 114, and then outputs it to the output terminal 116. In this case, the input signal is voice-encoded in the voice encoder 114, and is output as an encoded audio signal.
Since the conventional voice transmitter and the voice encoder are configured as described above, if the transmitter detected and judged false an audio signal to be a DTMF signal during a telephone conversation, an output signal, which is decoded in the DTMF encoding unit 11 or in the DTMF encoder 113, will be transmitted to a destination equipment. Thus, the destination side equipment, which is received this signal, is obliged to generate a DTMF signal based on the decoded signal. As a result, a destination caller will hear suddenly a sound of the DTMF signal, which gives an unpleasant feeling to the caller.
The present invention has been made to solve the above problems, and an object thereof is to provide a high-quality voice transmitter, which does not give an unpleasant feeling to a caller, even when the transmitter detected and judged false an audio signal to be a DTMF signal during a telephone conversation, and which can transmit the a signal reliably when the DTMF signal is actually transmitted.
A voice transmitter according to the present invention for encoding and transmitting a DTMF signal and an audio signal, includes:
voice encoding means for performing voice-encoding of an inputted audio signal;
DTMF encoding means for performing encoding of an inputted DTMF signal;
voice-DTMF encoding means for performing voice encoding of an inputted audio signal and a DTMF signal;
a first selector for selecting the DTMF signal encoded in the DTMF encoding means, or the DTMF signal voice-encoded in the voice-DTMF encoding means;
DTMF transmission control means for monitoring quality of an input signal and a transmission line, congestion of the transmitter, or a call connection, and for controlling selecting operation of the first selector depending on the state;
DTMF detecting means for detecting that an inputted signal is a DTMF signal; and
second selector for selecting an output of the voice encoding means when the DTMF detecting means judged the inputted signal not to be a DTMF signal, and for selecting an output signal selected by the first selector when the DTMF detecting means judged the inputted signal to be a DTMF signal.
In the voice transmitter according to the present invention, the voice-DTMF encoding means voice-encodes both an audio signal and a DTMF signal at a higher speed than a voice-encoding speed of the voice encoding means.
In the voice transmitter according to the present invention, the voice-DTMF encoding means incorporates an encoding algorithm, which is specialized in a DTMF signal, and encodes the DTMF signal of poor voice quality at the same speed as a voice-encoding speed.
In the voice transmitter according to the present invention, the DTMF transmission control means is call connection state monitoring control means for monitoring a call connection state, and for, depending on the call connection state, controlling the first selector to select either an output of a DTMF encoding unit or that of a voice-DTMF encoding unit for a DTMF signal transmission.
In the voice transmitter according to the present invention, the DTMF transmission control means is input-signal quality monitoring control means for monitoring quality of an inputted audio signal and a DTMF signal, and for, depending on the quality, controlling the first selector to select either the DTMF encoding means or the voice-DTMF encoding means for a DTMF signal transmission.
In the voice transmitter according to the present invention, the DTMF transmission control means is transmission-line quality monitoring control means for monitoring transmission quality on a transmission line, and for, depending on the transmission-line quality, controlling the first selector to select either the DTMF encoding means or the voice-DTMF encoding means for a DTMF signal transmission.
In the voice transmitter according to the present invention, the transmission-line quality monitoring control means is data-error-rate monitoring control means for monitoring a data error rate on a transmission line, and for, depending on the data error rate, controlling the first selector to select either the DTMF encoding means or the voice-DTMF encoding means for a DTMF signal transmission.
In the voice transmitter according to the present invention, the transmission-line quality monitoring control means is IP-packet loss-rate monitoring control means for monitoring an IP packet loss rate on the transmission line, and for, depending on the IP-packet loss-rate, controlling the first selector to select either the DTMF encoding means or the voice-DTMF encoding means for a DTMF signal transmission.
In the voice transmitter according to the present invention, the transmission-line quality monitoring control means is IP-packet delay-variation-quantity monitoring control means for monitoring incoming delay variation quantity of IP packet on a transmission line, and for, depending on the incoming delay variation quantity, controlling the first selector to select either the DTMF encoding means or the voice-DTMF encoding means for a DTMF signal transmission.
In the voice transmitter according to the present invention, the transmission-line quality monitoring control means is ATM cell loss-rate monitoring control means for monitoring an ATM cell loss rate on a transmission line, and for, depending on the ATM cell loss rate, controlling the first selector to select either the DTMF encoding means or the voice-DTMF encoding means for a DTMF signal transmission.
In the voice transmitter according to the present invention, the transmission-line quality monitoring control means is ATM cell delay-variation monitoring control means for monitoring an ATM cell loss rate on a transmission line and ATM cell incoming delay variation quantity on the transmission line, and for, depending on the ATM cell incoming delay-variation-quantity, controlling the first selector to select either the DTMF encoding means or the voice-DTMF encoding means for a DTMF signal transmission.
In the voice transmitter according to the present invention, the DTMF transmission control means is transmitter congestion state monitoring control means for monitoring a congestion state in the transmitter, and for, depending on the congestion state, controlling the first selector to select either the DTMF encoding means or the voice-DTMF encoding means for a DTMF signal transmission.
In the voice transmitter according to the present invention, the transmitter congestion state monitoring control means is freeze out ratio monitoring control means for monitoring a freeze out ratio, which is caused by congestion of an audio signal to be transmitted in the transmitter, and for, depending on the freeze out ratio, controlling the first selector to select either the DTMF encoding means or the voice-DTMF encoding means for a DTMF signal transmission.
A voice transmitter according to the present invention for encoding a DTMF signal and an audio signal and for transmitting the signals, includes
voice encoding means for performing voice-encoding of an inputted audio signal;
DTMF encoding means for performing encoding of an inputted DTMF signal;
first voice-DTMF encoding means for performing voice encoding of an inputted audio signal and a DTMF signal;
a second voice-DTMF encoding means for performing voice encoding of an inputted audio signal and a DTMF signal, and for outputting the encoded data, which is encoded at a higher speed and is of better quality than those of the first voice-DTMF encoding means;
first selector for selecting a DTMF signal encoded in the DTMF encoding means, a DTMF signal voice-encoded in the first voice-DTMF encoding means, or a DTMF signal voice-encoded in the second voice-DTMF encoding means;
DTMF transmission control means for monitoring quality of an inputted signal and a transmission line, congestion of the transmitter, or a call connection, etc., and for controlling selecting operation of the first selector depending on the monitored result;
DTMF detecting means for detecting that an inputted signal is a DTMF signal; and
a second selector for selecting an output of the voice encoding means when the DTMF detecting means judged the inputted signal not to be a DTMF signal, and for selecting an output signal selected by the first selector when the DTMF detecting means judged the inputted signal to be a DTMF signal.
In the voice transmitter, the DTMF transmission control means includes
transmission-line quality monitoring control means for monitoring transmission quality of a transmission line, and for, depending on the transmission line quality, controlling the first selector to select an output of the first voice-DTMF encoding means or that of the second voice-DTMF encoding means is selected in a first step; and
call connection state monitoring control means for monitoring a call connection state, and for, depending on the call connection state, controlling the first selector so that an output of the DTMF encoding means, or that of the first or the second voice-DTMF encoding means, which is selected in the first step, is selected in a second step for a DTMF signal transmission.
In the voice transmitter according to the present invention, the DTMF transmission control means includes
transmitter congestion state monitoring control means for monitoring a congestion state in the transmitter, and for, depending on the congestion state, controlling the first selector so that an output of the first voice-DTMF encoding means or that of the second voice-DTMF encoding means is selected in a first step; and
call connection state monitoring control means for monitoring a call connection state, and for, depending on the call connection state, controlling the first selector so that an output of the DTMF encoding means, or that of the first or the second voice-DTMF encoding means, which is selected in the first step, is selected in a second step for a DTMF signal transmission.
In the voice transmitter according to the present invention, the DTMF transmission control means includes:
transmission-line quality monitoring control means for monitoring transmission quality of a transmission line, and for, depending on the transmission quality, controlling the first selector so that an output of the first voice-DTMF encoding means or that of the second voice-DTMF encoding means is selected in a first step; and
input-signal quality monitoring control means for monitoring quality of an inputted audio signal and a DTMF signal, and for, depending on the quality, controlling the first selector so that an output of the DTMF encoding means, or that of the first or the second voice-DTMF encoding means, which is selected in the first step, is selected in a second step for a DTMF signal transmission.
In the voice transmitter according to the present invention, the DTMF transmission control means includes
transmission congestion state monitoring control means for monitoring a congestion state in the transmission, and for, depending on the congestion state, controlling the first selector so that an output of the first voice-DTMF encoding means or that of the second voice-DTMF encoding means is selected in a first step; and
input-signal quality monitoring control means for monitoring quality of an inputted audio signal and a DTMF signal, and for, depending on the quality, controlling the first selector so that an output of the DTMF encoding means, or that of the first or the second voice-DTMF encoding means, which is selected in the first step, is selected in a second step for a DTMF signal transmission.
In the voice transmitter according to the present invention, the DTMF transmission control means is transmission-line quality monitoring control means for monitoring transmission quality of a transmission line, and for, depending on the detected level of the transmission quality, controlling the first selector so that an output is selected from any one of those including the first voice-DTMF encoding means, the second voice-DTMF encoding means, and the DTMF encoding means.
In the voice transmitter according to the present invention, the DTMF transmission control means is transmitter congestion state monitoring control means for monitoring a congestion state in the transmitter, and for, depending on the detected level of the congestion state, controlling the first selector so that an output is selected from any one of those including the first voice-DTMF encoding means, the second voice-DTMF encoding means, and the DTMF encoding means.